the latest on that seattle man on trial for murdering his wife, more than seven years after she was killed. David pietz chose not to testify in his own defense. So, the jury will start hearing closing arguments today. Abc's neal karlinsky is tracking the case. The defendant is declining to take the stand in his own defense? That's correct, your honor. Reporter: Not only will david pietz not be testifying in his own defense, his attorneys' actions, putting on only two witnesses, seem to believe that they don't believe prosecutors have proven they're case. Haven't proven that pietz strangled his wife, nicole, and dumped her body in the woods. Their main point that she may have had a drug problem. A theory they've explored as a possible explanation for her murder. Her former doctor testified that nicole was prescribed painkil painkilpainkil painkillers because of deavere back pain. She was not to use more than eight a day. Was that because of your concerns about addiction? Addiction and her medical problem. Reporter: Prosecutors pounced. Pointing out the doctor's statements that nicole was so concerned about her own past abuse, she wanted fewer drugs. There was no withdrawal. There was no drug-seeking behavior. There was no sign that you saw in her that she was relapsing in any other way, other than the fact she was getting prescriptions, correct? That is correct. Reporter: Prosecutors revealed their final piece of circumstantial evidence. A tennis bracelet that nicole used to wear, which authorities say david pietz had said vanished along with his wife in 2006. A former coe worker testified that pietz showed her that very bracelet in the hopes of selling it. I had actually taken the bre bracelet and put it around my wrist. He started laughing. And he goes, oh, my gosh. That's so weird. I looked up and said, what? He said, you're wearing my dead wife's bracelet. Reporter: She called police about the bracelet. Is it enough? Weeks of testimony about mistresses, lies, descriptions of a man in a marriage he wanted out of. Through it all, david pietz has maintained his innocence. Closing arguments are scheduled to begin later this morning. Let's talk to abc's chief legal affairs anchor, dan abrams about this. Two witnesses called by the defense. False confidence? This is not a surprise to me. This case is about forcing the prosecution to prove its case beyond a reasonable doubt. I'm actually even a little surprised the defense is pursuing this -- the dead woman was taking drugs and maybe this was sort of drug-related, et cetera. So, I'm even surprised they're presenting evidence about that. This is a case that took the prosecutors a long time, many, many years, to bring. Why? Because they didn't feel they had enough evidence. They got a couple of new developments with regard to new technology, et cetera, that allowed them to bring this case. This is not an easy case. One piece of physical evidence, this tennis bracelet. That's always been one of the most important pieces of evidence for prosecutors. It shows that he lied. He said that that bracelet disappeared. And then, lo and behold, not only did it not disappear, not only did he not forget about it, there he is. And you see a witness testifying about the fact he's trying to appraise it. And how much is this diamond bracelet worth? One of the keys to the prosecution's case here, is showing he wasn't being truthful. That will be the crux of the closing argument? A good part of it, in addition to dna, cell phone records, et cetera. They have to piece together this puzzle. I think their concern is going to be that the jurors will think, yeah, he could have done this. Yeah. I definitely have suspicions that he did this. But do we have proof beyond a reasonable doubt? Dan abrams, thanks very much.

This transcript has been automatically generated and may not be 100% accurate.

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